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arXiv 0712.0345astro-ph
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LSB镓的化学演化

The Chemical Evolution of LSB Galaxies

Lars Mattsson, Brady Caldwell, Nils Bergvall

摘要:

我们推导出的晚型,低表面亮度(LSB)星系的样本中发现的斯隆数字巡天(SDSS)的氧和氮丰度。此外,我们还计算了一个大网格(5000个模型)的化学演化模型(CEMs)测试各种时间尺度的下降,重子密度和几个幂律初始质量函数(IMF)以及。由于在CEM(对于给定的IMF)和观测中发现的相当稳定的N/O趋势,我们发现LSB星系的恒星星族由低质量恒星主导的假设,即,底部非常重的IMF(见Lee et al. 2004),可以排除。这些模型预测的N/O比太高,而O/H比通常太低。我们还得出结论,LSB星系可能有相同的年龄,他们的高表面亮度对应,虽然全球的恒星形成率必须在这些星系相当低。

英文摘要:

We have derived oxygen and nitrogen abundances of a sample of late-type, low surface brightness (LSB) galaxies found in the Sloan Digital Sky Survey (SDSS). Furthermore, we have computed a large grid (5000 models) of chemical evolution models (CEMs) testing various time-scales for infall, baryon densities and several power-law initial mass functions (IMFs) as well. Because of the rather stable N/O-trends found both in CEMs (for a given IMF) and in observations, we find that the hypotheses that LSB galaxies have stellar populations dominated by low-mass stars, i.e., very bottom-heavy IMFs (see Lee et al. 2004), can be ruled out. Such models predict much too high N/O-ratios and generally too low O/H-ratios. We also conclude that LSB galaxies probably have the same ages as their high surface brightness counterparts, although the global rate of star formation must be considerably lower in these galaxies.

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